1. Field of the Invention
The present invention relates to an exposure apparatus for printing plates, which takes a printing plate out of an accommodating cassette which accommodates printing plates and records an image onto the printing plate.
2. Description of the Related Art
In a conventional exposure apparatus for printing plates, for example, an accommodating cassette is loaded. In the accommodating cassette, a plurality of printing plates (e.g., photopolymer plates), in which photosensitive layers (e.g., photopolymer layers) are provided on supports, are accommodated in a stacked state. The accommodating cassette is provided with an opening which opposes an exposure surface (a surface at a photosensitive layer side) of the printing plate. The opening is provided with an open-close shutter. Accordingly, the open-close shutter is slid in an opening direction in a darkroom, and the printing plates are accommodated in the accommodating cassette in the state in which the opening is opened. After that, the open-close shutter is slid in a closing direction, and, for example, the accommodating cassette is loaded into the apparatus in the state in which the opening is closed. As a result, the printing plates are prevented from being unnecessarily exposed to light and thus image quality is not adversely affected.
In these types of exposure apparatus for printing plates, the open-close shutter is slid in the opening direction inside the apparatus, and the printing plate is taken out of the accommodating cassette in the state in which the opening is opened, and then, an image is recorded onto an exposure surface of the printing plate.
However, in these exposure apparatus for printing plates, the open-close shutter needs to be curved when the open-close shutter is slid in the opening direction, and thus, the open-close shutter has a structure in which a plurality of wide-short plates are tiltably connected to each other (shutter known as a bellows type). As the open-close shutter having such a structure is thick, the accommodating cassette is also thick. Therefore, the accommodating cassette was very heavy. Accordingly, the accommodating cassette was not easy to lift, and thus, there was a problem that operation of conveying the accommodating cassette is difficult (conveying the accommodating cassettes required a lot of strength).
Further, in these exposure apparatus for printing plates, a bracket is provided at a leading end of the open-close shutter in the closing direction, and actuator sensors are provided inside the accommodating cassette so as to correspond with the bracket. When the bracket contacts the actuator sensors, the states in which the open-close shutter is opened and closed are detected. As the bracket protruded outside the opening of the accommodating cassette, there was a possibility that safety was compromised, and further there was a problem of inferior design as well.
In consideration of the above facts, it is an object of the present invention to obtain an exposure apparatus for printing plates, which can facilitate the operation of conveying the accommodating cassette.
A first aspect of the present invention is an exposure apparatus for printing plates, into which is loaded a cassette, having therein a predetermined number of printing plates accommodated in a stacked state and which takes the printing plates out of the cassette, and records an image onto an exposure surface of each of the printing plates; wherein the apparatus comprises: an opening for accommodating the printing plates into the cassette and for taking the printing plates out of the cassette, which opening is provided at a portion of the cassette which portion opposes the exposure surface of the printing plate; and a shutter provided at the opening, the shutter comprising a flexible structure slidable to a closed position closing the opening to the cassette, and to an open position, in which the opening to the cassette is open.
In the exposure apparatus for printing plates according to the first aspect of the present invention, the flexible shutter is slid in the opening direction so as to open the opening of the accommodating cassette in a darkroom, and in this opened state, a predetermined number of printing plates which are stacked are accommodated into the accommodating cassette through the opening.
After that, the shutter is slid in the closing direction so as to close the opening, and in this closed state, the accommodating cassette is loaded into the apparatus. As a result, even if light is emitted from the outside of the accommodating cassette, the printing plates can be prevented from being unnecessarily exposed to light and thus their quality is not adversely affected.
After the accommodating cassette has been loaded into the apparatus, the shutter is slid in the opening direction so as to open the opening. In this opened state, the printing plate is taken out of the accommodating cassette through the opening, and an image is recorded onto an exposure surface of the printing plate.
The shutter is configured as a thin plate, and thus, the accommodating cassette can be accordingly thin. As a result, the accommodating cassette is lightened such that the operation of conveying the accommodating cassette can be facilitated (conveying the accommodating cassette does not require much strength).
A second aspect of the present invention is an exposure apparatus for printing plates, wherein the opening includes a periphery having opposite sides, with a groove defined in each side, and the shutter includes opposite peripheral edges which are each received in a groove and slide therealong as the shutter is moved to the closed and open positions.
According to the exposure apparatus for printing plates, in the state in which the opening of the accommodating cassette is closed by the shutter, the peripheral edge of the shutter is inserted into the light-shielding groove formed at the periphery of the opening. Accordingly, even if a special light-shielding member is not used, the printing plates can be completely prevented from being unnecessarily exposed to light and thus their quality is not adversely affected.
Further, as described above, a special light-shielding member does not need to be used, and thus, the accommodating cassette can be thinner. As a result, the accommodating cassette is made even lighter such that the operation of conveying the accommodating cassette is further facilitated.
A third aspect of the present invention is an exposure apparatus for printing plates, further comprising sprockets rotatably mounted in the cassette, the sprockets including engagement pins and the shutter including engagement holes corresponding to the engagement pins, with the shutter entrained around the sprockets and moving to closed and open positions when the sprockets rotate.
In the exposure apparatus for printing plates, when the sprockets provided in the accommodating cassette are rotated, the engagement pins of the sprocket sequentially engage with the engagement holes of the shutter, and the shutter is slid. As a result, an operation of sliding the shutter becomes smooth, and the operation of opening and closing of the shutter can be carried out satisfactorily.
A fourth aspect of the present invention is an exposure apparatus for printing plates, wherein the engagement holes are circular and the engagement pins have a circular cross-section.
In the exposure apparatus for printing plates, since the engagement hole of the shutter is circular, and a cross-section of the engagement pin of the sprocket is circular, load applied when the engagement pin engages with the engagement hole is dispersed. Accordingly, the shutter and the sprockets can be prevented from being broken or deformed.
A fifth aspect of the present invention is an exposure apparatus for printing plates, further comprising: a detection member provided on the shutter and movable with the shutter when the shutter moves to open and closed positions; and sensors provided in accordance with locations of the detection member when the shutter is in the open and closed positions, the sensors detecting proximity of the detection member and producing an electronic output indicating when the shutter is in the open and closed positions.
In the exposure apparatus for printing plates, when the sensors, which are provided so as to correspond with positions of the member for detection in the states in which the shutter is opened and closed, detect that the member for detection is in proximity thereto, the state in which the shutter is opened or closed is detected.
Since the member for detection is provided at the rear end of the shutter in the closing direction, the member for detection is always positioned inside the accommodating cassette so as not to be exposed at (protrude from) the opening. Accordingly, safety and design is satisfactory.
Furthermore, as described above, the member for detection does not protrude from the opening of the accommodating cassette, and thus, the accommodating cassette can be even thinner. As a result, the accommodating cassette is made even lighter such that the operation of conveying the accommodating cassette can be facilitated even more.
A sixth aspect of the present invention is an exposure apparatus for printing plates, further comprising casters mounted to the cassette, which support the cassette and provide for rolling the cassette along a surface.
In the exposure apparatus for printing plates, casters are provided at the bottom portion of the accommodating cassette, and thus, the accommodating cassette can be conveyed in the state in which the accommodating cassette is supported by the casters. As a result, regardless of weight of the accommodating cassette, the operation of conveying the accommodating cassette can be reliably facilitated.